Jump to main content
US EPA
United States Environmental Protection Agency
Search
Search
Main menu
Environmental Topics
Laws & Regulations
About EPA
Health & Environmental Research Online (HERO)
Contact Us
Print
Feedback
Export to File
Search:
This record has one attached file:
Add More Files
Attach File(s):
Display Name for File*:
Save
Citation
Tags
HERO ID
1568316
Reference Type
Journal Article
Title
Mechanisms for the Reaction of Thiophene and Methylthiophene with Singlet and Triplet Molecular Oxygen
Author(s)
Song, X; Fanelli, MG; Cook, JM; Bai, F; Parish, CA
Year
2012
Is Peer Reviewed?
1
Journal
Journal of Physical Chemistry A
ISSN:
1089-5639
EISSN:
1520-5215
Volume
116
Issue
20
Page Numbers
4934-4946
PMID
22515263
DOI
10.1021/jp301919g
Web of Science Id
WOS:000304338600014
Abstract
Mechanisms for the reaction of thiophene and 2 methylthiophene with molecular oxygen on both the triplet and singlet potential energy surfaces
(PESs) have been investigated using ab initio methods. Geometries of various stationary points
involved in the complex reaction routes are optimized at the MP2/6-311++G(d, p) level. The
barriers and energies of reaction for all product channels were refined using single-point
calculations at the G4MP2 level of theory. For thiophene, CCSD(T) single point energies were also
determined for comparison with the G4MP2 energies. Thiophene and 2-methylthiophene were shown to
react with 02 via two types of mechanisms, namely, direct hydrogen abstraction and
addition/elimination. The barriers for reaction with triplet oxygen are all significantly large
(i.e., >30 kcal mol(-1)), indicating that the direct oxidation of thiophene by ground state
oxygen might be important only in high temperature processes. Reaction of thiophene with singlet
oxygen via a 2 + 4 cycloaddition leading to endoperoxides is the most favorable channel.
Moreover, it was found that alkylation of the thiophene ring (i.e., methyl-substituted thiophene)
is capable of lowering the barrier height for the addition pathway. The implication of the
current theoretical results may shed new light on the initiation mechanisms for combustion of
asphaltenes.
Home
Learn about HERO
Using HERO
Search HERO
Projects in HERO
Risk Assessment
Transparency & Integrity